In a gyratory crusher of the type depicted, intermesh relationship between the drive pinion and the driven gear can vary considerably due to machining tolerance of the machined parts and clearances in the outer bearing and also due to the tolerance of the gears. In order to maintain correct running clearances between the drive pinion and the driven gear, it is necessary to adjust the backlash between the gears to a predetermined desired setting. In prior art crushers, the backlash adjustment is made by means of steel shims to change the relative position of the drive pinion and the driven gear. In using shims for effecting such adjustment it is necessary to disassemble and reassemble several parts of the machine. This is a time consuming and relatively costly method of effecting the adjustment.